Sensei Biotherapeutics acquires Faeth Therapeutics, agrees to $200 million private placement

Sensei Biotherapeutics, Inc. (Nasdaq: SNSE) completed its acquisition of Faeth Therapeutics on February 17, 2026. On the same day, it signed a securities purchase agreement to sell about $200 million of Series B non-voting convertible preferred stock in a private placement. The company disclosed both in a Form 8-K filed February 18, 2026.

How the acquisition was structured

Under a merger agreement dated February 17, 2026, Sensei's first merger subsidiary merged into Faeth Holdings Therapeutics, Inc., called HoldCo in the filing. HoldCo then merged into a second Sensei subsidiary.

Sensei issued HoldCo's stockholders 10,602.3880 shares of Series B preferred. Each share converts into 1,000 shares of common stock, subject to conditions. The press release says Faeth's equity was exchanged for 252,210 shares of Sensei common stock and about 10,604 shares of Series B preferred, on a fully diluted basis. The board approved the deal unanimously, and the merger did not require a Sensei stockholder vote.

The private placement

Under the purchase agreement, dated February 17, 2026, Sensei agreed to sell approximately 14,440 shares of Series B preferred for about $200 million in cash, before placement agent and other offering expenses. The release puts the price at about $13,850 per preferred share, or about $13.85 per share on an as-converted basis. The shares are exempt from registration under Section 4(a)(2) of the Securities Act and Regulation D, and Sensei must file a resale registration statement within 75 calendar days after the financing closes.

Participants named in the release include B Group Capital, Balyasny Asset Management, Columbia Threadneedle Investments, Cormorant Asset Management, Fairmount, Logos Capital, RA Capital Management and Vivo Capital. Leerink Partners is the exclusive placement agent. Lucid Capital Markets is financial advisor to Sensei, and Cantor and Citi are capital markets advisors on the financing. Sidley Austin LLP is Sensei's legal counsel, and Cooley LLP is counsel to Faeth.

Dilution and the votes needed

The 8-K says that right after the merger, Sensei's pre-deal holders would own about 10.7% of the common stock on a fully diluted, as-converted basis, and former Faeth holders about 89.3%. After the financing, Sensei's earlier holders would own about 4.9%, former Faeth holders about 40.8%, and the new investors about 54.3%.

Sensei has agreed to hold a stockholder meeting on several proposals. They include approval of the preferred conversion and a change of control under Nasdaq Listing Rules 5110 and 5635(b). They also include an increase of up to 300,000,000 authorized common shares, and a reverse stock split of between 1:2 and 1:12 if the company or Faeth decides it is needed for Nasdaq listing compliance. Stockholder support agreements cover about 1.6% of the pre-transaction shares.

The lead program and its data

Sensei says it will use the proceeds mainly to advance PIKTOR, an all-oral combination of serabelisib and sapanisertib that inhibits the PI3K/AKT/mTOR pathway. The company expects topline data from an ongoing Phase 2 trial in second-line advanced endometrial cancer, and the start of a Phase 1b trial in HR+/HER2- advanced breast cancer, both by year end 2026. The rest goes to general corporate purposes and a Phase 1/2 trial of solnerstotug, a VISTA inhibitor.

The release cites a completed Phase 1b trial in which PIKTOR plus paclitaxel produced an overall response rate of 47% in response-evaluable patients, with n=15. The patients had averaged four prior lines of therapy. The 71% response rate reported for patients with PI3K pathway mutations is a subgroup, and the release counts three complete responses. Fifteen patients is a small sample, and a subgroup rate rests on fewer still. The release does not say whether the study was controlled.

Anand Parikh, a Faeth co-founder, is now Sensei's Chief Operating Officer and a director.

Money and what is missing

Chairman Bob Holmen said in the release that "we believe the company is well capitalized to execute through key clinical milestones in endometrial and breast cancer." That is the company's own assessment; the 8-K and release give no Sensei cash balance, net loss or cash burn. The release puts the total at approximately 26,304,468 common shares on an as-converted basis, and the preferred converts only after Sensei stockholders approve.

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